The report is based on conversations with a "key component supplier" to Apple.

Here's the full note:

"Supporting out comments over the last month, conversations with yet another key component supplier indicates that production for iPhone-5 will begin in September. This is consistent with Avian findings in the supply chain in recent months and we believe the consensus view is moving towards this scenario. In addition, our conversations also indicate the existence of a lower-spec/lower-priced iPhone in Apple's roadmap. However, while our contacts have seen the placeholder in the Apple roadmap, they do not yet have insight into specs or production timing. This leads us to believe that any launch is likely a very late 2011 or more likely a 2012 event. As a reminder, Avian has uncovered several data-points in recent months pointing to the existence of a lower-spec/lower-price iPhone. A lower-spec/lower-price iPhone has also been speculated in the press and gadget blogs, though we do not believe consensus currently discounts the existence of such a model."